Fluid pressure motor



J. w. RUSH ETYAL 2,413,380

FLUID PRESSURE MOTOR Filed Aug. 31, 1944 :Figi

Iig. 2

lNVENToRS Jbhn WRuSh Arthur Bent Ww ATTORNEY vatentecl Dec. 31, 1946 UNITED' STATES PATENT (5l-:FICE

FLUID PRESSURE MOTOR; John W. Rush` and Arthur JL Bent, Wilkinsburg'i Pa., assignors to The Westinghouse Air Brake Company, Wilni'eiding, Pa., a' corporation1 of Pennsylvania 7' Claims.

1. I This invention relatesto' control devices and more particularly to the type adapted to be controlled and operated' by fluid under pressure.

n the copending application of Rankin J. Bush', Serial No. 480,161, ledy March 23, 1943, and assigned to the' assignee of the present application, there is disclosedy a fluid' pressure controlsystem for controlling a plurality of internel combustion engines, such as employed for propelling an airplanasaid system comprising for each engine a plurality of iiuid motors, one for controlling theenginespeed, another for controlling the richness of the-'fuel mixture supplied to the engine, still another forv controlling the temperature of the mixture, and a fourth for controlling operation of a blower or superch'arger for the engine.

One *object of the invention is the provision of an improved fluid motor for controlling devices or" the above general type; Another object of the invention is the provision of a fluid motor for con'- trolling .Operation of a device such as above mentioned and" which embodies mean-s 4automatic'ally operative in case of failure'of the supply of fluid under pressure for controlling operation of the lIn the accompanying drawing: Fig. 1 is a lony gitudinal sectional view, partly in diagrammatic motor, for moving said 'device to and for hold-g vof a fluid motor embodyin'gfluid operated power piston meansand an operators flu'id'pressure controlled pilot means which is constructed to be very sensitive to' changes in controlling pressure and therefore accurately adjustable in accordance with fine' increments of Asuch change, so as to render the pov/er means accurately andv positively adjustable in accordance with 4cl:'1an$.,ires in the pressure of controlling fluid on `the pilot means.

Another object of tlieinven'tion is the provision of a fluid motor embodying power piston means which is' so constructed and controlled as" vto m'o've to and 4positively stop in any position selectedby operation 'of the pilot portion of the motor, that is to say,'the power piston means'fwill not overtr-'a'vei the selected position nor will' it oscillate to either onersid'e or the other' of such position. v

Another` object of the invention is the provisionv` 'of 'a' motor of the above type which is relatively smali in size, compact and simple in construction, and light in weight for the' purpose intended.

Other objects and advantages Will be apparent from the following more detailed description of the invention,

form, of one embodiment of the invention; and Fig. 2A is a view similar to Fig. 1 of a modified form of the invention. Y

Description-Fig. 1

The fluid motor shown in Fig. I of the drawing comprises a cylindrical casingl I one end otwhich is closed by a cover 2, while the opposite .end ifs closed by acover 3, and intermediate the `ends of the casing there is provided an internal wall li. A flexible diaphragm 5- is clamped around-its peripheral edge between the casing I andV cover 2 and has at one side aI chamber 6 @pento a combined control and-fluid pressure supply pipe 'I. At the opposite side `lof diaphragm 5 is- ,a chamber 8 formed between the diaphragm and casing iva-114. The chamber 8 is in constant communication with atmosphere through a passage f9.

At the opposite side of wall 4 the casing' ,I has a piston bore I-. -The cover 3 has ia; piston bore I ispacedaxi'ally from and arrangedin contcentric relation vto the borev II). One end off-bore H `is open to the bore Ifl) whiley the opposite end his closed Vby a w'all I2 constituting a portion Jot the cover 3.3 Thebore .Ii isof smaller diameter than bore Nl' andslidably' mounted inthose bores are pistons I3 and I4, respectively, each havin-g a ring! groove in which is' mounted a packing ring I 5 having' sealing sliding contact with the wall of the` respective bore. fIlie--tvvopi'stc'in heads I3 and 'I4 are axially aligned andi connected vfor movement in unison and constitutea diierential area power piston means v3u. Between-the-pis'ton 'head I4 and wall Athere i'slprovideda-iiuid -p'ressure control chamber Iiil Between the -twopressureheadsl i3" and III'is a'dash-pot chamber -I"l. Between the piston l'leadv I3 and the end wall I12 ofco'ver 3 is a chamber I8 which is in constant communication with atmospherethrougha: `passage ISL The wall I'2`- of cover 'f3 i`s provided with a- `bore axially aligned with the piston heads" I3 and 14, and projecting through this bore ffrom lthe pistonneau' 1.3 is a: piston rod-'2m outside-of cover perforated flange 32.

25 is fulcrumed on a pin 26 which is carried by an ear 21 projecting from the cover 3. In the opposite end of lever 23 is an opening 28 which is provided to receive a pin or the like for connecting said lever to a device which it is desired to operatebyr. the .moton The lever: 23 hasra normal positionfin which it isshown in the drawiing and is movable out of this position by the power piston means 39, as will be later described.

The flexible diaphragm is of the type com'- prising an annular corrugation 3 I, an outer flange encircling said corrugation for clamping between the casing section I and cover 2,` and 'an inner tion 34 extending through the central opening in diaphragm 5, while a follower 35 containedin chamber 8 is secured to this stud portion by screw threaded engagement for clamping the central flange 32 of the diaphragm between the two followers. A-coil type regulating spring 36 arranged `in coaxial relation with the diaphragm 5 and vpower piston means 38 is contained in chamber 8 and is supported at one end Yon the casing wall 4 while its opposite end bears against the dia'- phragm follower 35V. This spring is under pressure and therefore effective to deflect the ydiaphragm and move the followers 33 and 35 against :pressure of fluid in chamber 6 and in thedirection of a stop 3l provided in cover 2. Shims 36a may be employed between wall 4 and the adja- -cent end-of Ythe spring 36 for adjusting its pres- -sure against diaphragm 5.

il `'Ihecasing wall 4 is provided which extends into chamber 8 within the regulatwith a boss 38 ing spring 36. Extending through the boss 38 and slidably mounted therein in .coaxial relation With-*the piston means 30 and-diaphragm 5 is an-.operating rod 39. One end of the rod 39 projects into chamber I6' atone .side of the power piston means 3U, while the opposite end is disposed in chambers. The boss 38 is' provided with -v Infhe endof that portion of the rod 39 which -is disposedin chamber 8 there is provided a semispherical socket in which is disposed a ball-like end 4 4 of ia link 45, said end 44 being secured in said socket by a member 46 secured to the end of rod 39 by Va nut 41. The link A45 has at its opposite end a Y,ball-like'structure 48 which -isl seated ina socket in the end of the diaphragm follower stud 34, and which is secured to said stud by a member 49 urged into contact with the ball-like end by a fiange 59 projecting from the diaphragm followerv V3 5; Projecting from the diaphragm follower 33' 'intofa'borein cover 2 is a member 5I having at 4-its .end a ball-like structure 52 of larger diameter than said member and in substantial contact with the Wall of said bore.z The ball and'socketv "connections between the opposite ends of link 45 fand the operating rod 39 and diaphragm follower 33, 4and between the cover 2 and ball-like end52 at the end of member'5l are provided to allow th'e diaphragm 5to freely rock or' tilt relative to member 39 in a direction or directions'which will A diaphragm follower 33 contained in control chamber 6 has a stud por- `through a passage 55.

4 rock the axis of the diaphragm, in order that the diaphragm may freely adjust itself to the regulating spring 36 without causing binding of the operating rod 39 within the boss 38. This structure is adapted to render the diaphragm very sensitive to slight changes in pressure in control tchamber 6,A and therefore accurately adjustable in accordance with such changes in pressure.

A sealing ring 53 is disposed in a, groove provided in the ball-like structure 52 and has sealing Y and sliding contact with the wall of the bore ln which said structure operates, in order to prevent leakage of vfluid under pressure between chamber Gat one side of the structure and chamber 54 at the opposite side.

Chamber 54 is in constant communication with the power chamber I6 The link is provided with anaxial passage 56 open at one end to a passage 5'! in the diaphragm follower 33 and open at the opposite end to a passage 58 in the operating rod 39'. .Ring like seal members 59 are provided in the ball-like; ends of link 45 and have sealing andsliding contact with the walls of the .respective socketsfor' preventing leakage of fluid under pressure from these passages to chamber 8. Passage 57 in the diaphragm follower 33 is open Vto control chamber 6, so that fluid under pressure effective in said chamber may ow through said passage and passage 56 to passage 58 in the operating rod39. Within boss 38 the operating rod 39 is provided with one or more radial bores 69 connecting passage 58 to the annular chamber 40,` whereby the control chamber 6 and dash-pot chamber I'I between the piston heads I3 and I4 -of the p ower piston means 38 are in constant communication. l V

In the power chamber I5 the operating rod 39 is connected to and supports a valve contro1 member 6I which has a chamber 62 containing a fluid pressure supply valve 63 and a spring 64 acting on said valve for urging it to a closedor seated vpositionin which itis shown in the drawing. The

passage 58 in operatingV rod 39 is open to chamber.V 62 whereby said chamber is adapted to be `constantly supplied with fluid under pressure .from the control chamber 6.

The supply valve 63 is arranged in coaxial relation with the powerpiston means 38 and has a'lstem 65 projecting Athrough a bore in the valve control member 6I into a chamber 66 in the power piston means 36. The chamber 63 is open at all times past the valve member 6I to the power chamber I5 and contains a fluid pressure release valve 61 arranged Vin coaxial relation with the supply valve stem 65 and to which said release valve 'is secured, whereby the two valves are movable in unison.

The release valve 61 isV adapted to cooperate with a seat provided onthe power piston means 3l] around one end of apassage 68 extending into -the piston rod 28 for thereby controlling communication between said passage and the power chamber I6.` In cover 3 an annular chamber 69 is provided around the piston rod 20 and is connected to a fluid pressure release pipe l0. The piston rodY 20 is provided with a radial port 1I connecting passage 68 in the rod to the annular chamber 69. Beyond each of the opposite ends of chamber 69 the cover 3 carries a ring seal member I2 having sealing and sliding contact with vsaid rod to prevent leakagelof fluid under pressure from chamber 69 to atmosphere.

The radial release port Il is of relatively small area constituting in effect a choke for limiting the rate of release of fluid under pressure from :arranco .chambers 66 .and .l- .fto afdegree havinga :certain 'relation lto .the flow capacit-,y ..of ,choke 412,. v:Likewise, there is .a .certain .relation abetween choke .42 :and v:the :rate atwhich fluid .may besuppli'ed past the supply valve i655 :tochambers :65 and :L6 and .this relation may :be .obtained `bygthe .supply valve stem E5 reducing :the .area .of the opening through the valve .control member 36| v,in which said stem is disposed,1to.a.deg-ree .which provides the required choking efect .to .obtainisaid relation. The size of these openings.rasshownginthe vdrawing are merely illustrative.

rllhe release pipe 1.9 imay lead .directly to atmosphere or it may lead to .a soecaglled sump reservoir provided forreceiying fluid .undertpressure-after it `Ahas been usedlforeiiecting axdesired operation. The .pressure of iiiuidy in ythensunlp reservoir .may .at times `exceed that of. :the atmosphere, Vhence the .useiof :the .sea-ling rings l2. Whetherthe pipe z'ifleads to .the atmosphere or tto a sump reservoir .is however immaterialgto thepresent invention. A sump reservoir Iof the .type under consideration is however Vshown and iully described inthe copending. application 'hereinbeforey referred to and, if desired, reference.

maybe madel to that applicationk fora more'complete description thereof.

The valve control member .al isprovidedwith an annular collaror fiange13for engaging .the innersuriace :1d-of amember 'T5 provided in .the power pistonmeanssll, whereby movement ofthe valve control member 6l `by the operating .rod 39 .in the direction .of the casingfcover will .pull the power piston means 3i! to the position in which .it is showninfthe drawing. .At .the-.opposite side of flange .T3 on valve memberil vrthere is clearance space provided to allow movement ,of said .valve .control `rnemberrelative to thle power piston means B a distance suflicient :te

open thesupply valve 63 without saidmember .g

contacting a shoulder `or surface gfdin charnber It willbe noted thatthe operating rod 3,:valve control member'fil, `andthe supply .Land release valves E and .67, respectively, .are supportedby the casing wall 4, lindependently of .the pilot means including diaphragm .5 vand 'fol1owersi33 and 35, and .also independently of .the vpower piston means 3B, whereby saidzrod, memberand valves will at all times bemaintained in operative relation to the diaphragm :5 .and will lprevent binding of said rod .within :the looss38 incase of tilting of said diaphragmrelative tosaid member or,y if for vany reason .the power piston means. 30 should tend to bind in the bores in which it is disposed.

Operation-Fig. 1

It is intended that the control pipe 'i'i and thereby the control chamber 6 be normally charged with fluid at a pressure in `excess of atmospheric'pressure, such aseighty pounds,.and that the. operation of the motor to adjust lever v23 will be obtained by .varying the pressure `through a range, such as seventy pounds, above the eighty pounds.

Now let it be assumed that pipe 1 vand .the .Qontrolchamber 5 are charged with,uid at the normal pressure of eighty pounds. rIlhis pressure, eiective on diaphragm 5, will move Vs aid diaphragm, the followers .35.and 33, the .link 45, the operating member 3,9 and -Valve Vvcontrol member 6l against theopposng pressure .of the :regulating spring 36 to-,a position .in `which the -pressure of said spring will .haveincreasedftofa Y in pressure of duid .degreeito ,copnterbalance `@theipnbssure of .-nid' in chamber .6, .whereupon'suchzmovement willfcease. This position .may he adjusted ,toward or away from .the Ast op (shoulder V:il in pover 2 -by :the yuse .of shims 36a, .as '.willlbe apparent. i

:Fluid at the inormal pressure nf eighty :pounds `inpipe f1 andehamber :5 will .equalize :through passage i151 Lin the diaphragm follower :33, passage 516 in link 45, .passage 58 and .-portsizintheop- .erating :rod 339, `chamber Auand :passage litl tinto .the dashfpot :chamber 11:1 between fthe ftwotpiston :heads laand f1.4. Thepressurepf .luid3th11s dbf- .tained between :the :two pistonheads :1 3 aindzt will create a force, equal to said pressure .times the diierence in areas of the, twozpiston heads, which will :act tounge the power piston .means '30 in the directionof the -.diaphragrn 25.. The position lwhich the .diaphragm 15 .assumes when subject in chamber .toithe normal pressure of eighty pounds lis preferably so. adiustedby the shims 36a, thatthepower piston means 30 moving under the pressure of fluid in the .dash-mot .Chamber H, 4will vcontact the :casing Wall .a4 .at .the same time it .moves intoseatingengagement with the releasefva'lve 6;'1 .andihence iwithout opening the .supplyvalve 63. In :thedrawingzthe apartsf the motor are shown yin :the positions just erle.- scri'oed, which willbe assumed 'to be their '.normal positions, and .with the rpower piston :means' thus positioned, `the lever l23 vwill falso assume :a normalposition in whichit `is shown inthedraw.- ing. v

If .the operator now desires .to ;rock the icontrol lever Y3 `out .of .its normalzposition .in a polluter- .clcckwise direction, as .Viewed inthe draivnahe will increase the 1. pressure of .iiuid in ychambert through pipe I toadegree abovezthenorrnal pressure of eighty pounds. This increaseyin pressure `on .diaphragm 15 will vdeiiect lsaid diaphragm against the opposing force .of .thefregulatingspring' 36 toa new position in which thepressurezof .said spring is increased toa degree suicient .to counterbalance the pressure of uidin vsaid, chamber whereupon the diaphragm will cease imoving. This deflection .of diaphragm;5 :will fact v:through rod 39 to move the .valve'ontrolnnemberal .relative to the powerpiston :means 35.1, v.and 'vwithithe release valve "6l closed holding-thesupply'val-ve 63 againstmovement in this-direction, the `'valve control ,member El will zmove out `of .seating .iengagement lwith said supply valve. Fluid under pressure will then `rlow l'from the supply .valre chamberfEZ to the power piston :chamber Ida-nd when .the `pressure of fluid in.V chamber 1.6...is .thus

`increased sufciently withfrespectztorthe .ODIJQSing clockwise. direction outof its normal position.

After thediaphragm 5 ceases .movement inre- `sponse to the increase :in .pressure of fluid ,in

y.chamber 6. the movement of .the power 4piston means 3B by the f pressureV `offfluid charnberA lr6 will be relative .t0-the valve .Control memberl. The .supply valve 63-Wi11 move Withpistonrmeaus .3U-.relative to the valve controlimemberl :until said valve seats against-saidrvalve control member to cut-oir further now of iiuidvunderlpres- .sure topower piston chamberl. .When-the Asupply` of duidunder .pressure tdchamber [6 .is thus `cut 01?y thepower piston `means 30 land :lever 23 will stopin a :position determinedby the-posi- .tionof-the diaphragm `5 and thusv bythe ,increase in. pipe lendcqntrel einem Thelpress'ur f iluid required in power charnber IS'to operate the power piston means 30 and lever 23 will depend upon the resistance to movementof the device being controlled, so that at one time a relatively small increase in pressure chamber I6 may be adequate to effect such movement, while at another time or under a different condition a greater pressure will be required in said chamber. The pipe 1, being however charged with fluid at a pressure in excess of eighty pounds, constitutes a source of iluid at adequate pressure to insure operation of the power piston means 30 to actuate lever 23 as intended.

i It is desired to point out that the position to Y'which the power piston means 30 is moved corresponds to theposition of the diaphragm 5, and lthus the increase in pressure in pipe 1 over the normal pressure, and the structure provides for Aobtaining fluid in chamber I6 at a pressure su'icient to ensure such positioning of the power pis- :ton means.

If the operator now desires to cause rocking of '.the'lever 23 to a greater degree from its normal position, he will increase the pressure in pipe 1 :and diaphragm chamber 6 to a degree corresponding to the desired new position of lever 23, and the motor will again operate in the same manner as above described, to move saidy lever andlthen stop it in the new position, which position again corresponds, to the position of diaphragm 5.

It will now be apparent that the lever 23 can 36 to a maximum degree, the lever 23 will be moved to a maximumextent away from its normal position, as will also be apparent.

` The movement of the power piston means 30 as above described is opposed at all times by pressure of iluid in the dash-pot chamber I1,

4which is in constant communication with the'4 control pipe 1 through .the choke v42. It will thus be seen that when the pressure of fluid in pipe 1 is increased, the pressure in chamber l1 will also increase to provide a greater force for opposing movement of the power piston means.

This pressure in chamber l1 may even momentarfily increase to a greater degree than that in pipe 1 since movement of the piston head I4 by pressure of fluid in chamber I6 will reduce the volume of chamber I1 and choke 42 will restrict 'A outflow of fluid under pressure from said chamber, the degree of such increase depending upon and varying in proportion to the rate of movement of the power piston means 30 by pressure of iluid in chamber I6. If the rate of movement of the power piston means is relatively slow there may be substantially no increase in pressure in chamber l1 incident to the restricting elect of choke 42, however, if the piston means 30 .tends to jump or move rapidly upon supply of fluid to the power chamber I6, the pressure in chamber I1 will suddenly increase to such a degree as ,to lectively dampen and reduce the rate of movement of said piston means. This damping effect acting in conjunction with the limited or restricted rate of supply of iluid under pressure to the power .piston chamber I8 by way of the supply valve will then cause the power'piston means 30 lto positively stop V*as soon as the supply valve 63 seats, and hence in a position corresponding to the position of diaphragm 5 and the pressure of fluid in the control pipe 1, as above described. As soon as the power piston means 30 ceases moving, the pressure in chamber l1 will equalize with -that in the control pipe 1 by way of choke 42,

as will be apparent.

1f the operator now desires to rock the lever 23 back .toward its normal position he will reduce the pressure of uid in pipe 1 and diaphragm `chamberl. The regulating spring 36 will then act to move thediaphragm 5 to a position in which the pressure of said spring is eounterbalanced by the reduced pressure of fluid in chamber 6, whereupon the ldiaphragm will cease moving. This movement of the diaphragm and thereby of the operating rod 39 and valve control member 6l will be relative tothe power piston means 30, and with the supply valve 63 seated, said valve will drawthe release valve 61 away from its seat. Fluid under pressure will then be released from the power piston chamber I6 past the release valve 61 to bore 68 in the piston rod 20 and thence to the release pipe 1D.

When the pressure of fluid in the power piston 4chamber I6 is thus reduced suiliciently, the opposing pressure of iluid in chamber l1 will move the power piston means in the direction of the left-hand. After the diaphragm 5 ceases movement, this movement of the power piston means will be relative to the valve control member 6I and to the release valve 61 until the seat for the release valve moves into engagement therewith to prevent further release of iluid under pressure from chamber I6 in a position of the power piston means corresponding to lthe position of the diaphragm 5, and thus corresponding to the degree of reduction in pressure in the control pipe 1. The power piston means 30 will stop in this position for reasons which will be later described. This movement of the power piston means 30 will move the lever 23 back toward its normal position, but said lever will stop out of its normal position in a position determined by the reduc- :tion in pressure in chamber 1 and the position of diaphragm 5, as will be apparent.

In case the operator desires to return the lever 23 further in the direction of its normal position he will effect a further reduction in pressure of fluid in control pipe 1 and in diaphragm chamber 6 and the motor will again operate as above described -to correspondingly change the position of lever 23, as will be apparent. Upon reducing the pressure of fluid in pipe 1 and chamber 6 to the normal degree of eighty pounds, the lever 23 will be returned to its normal position as will also be apparent.

. It will `thus be seen that the operator can cause the lever 23 to be returned toward its normal position and to be stopped in any selected position out ofv normal position by reducing the pressure to effect return movement of lever 23, the pressure of iluid in chamber l1 will also tend to correspondingly reduce by now through choke 42.

`However, as the power piston means moves .to-

ward its normal position it will increasev the volume of chamber H and the choke means 42 is effective, in case the power piston means 39 tends to move too rapidly or to jump toward its normal position, to so restrict inflow .of `:duid pressure from control pipe 1 to said chamber, that the pressure in said chamber will reduce below .that in the control pipe to .a degree proportional to the rate of such movement. This reduction lin pressure in chamber `l'l will reduce the force on piston means 30 tending to return it to its normal position and this action plus the limited or .controlled rate of release of fluid under pressure from chamber IB by way of the relatively small n release port H is effective to stop the power pis-v .ton means 30 immediately upon obtaining a position corresponding to that of the diaphragm, and in which the release valve 61 seats.

It will now be seen thatdue to the use of choke 42, chamber Il acts in effect like a dash-pot, and it has been determined that thisstructure effectively prevents the piston means 3l] from overtraveling a position corresponding to the pressureA of fluid in the control pipe 7, and hence the position of the control or pilot diaphragm 5. This is very important, forin case the power piston means 30 were moving in response to an increase in pressure in chamber I6 and over-traveled, the release valve llil would be; opened and reduce thepressure of fluid in chamber i6, as a result of which, the direction of movement of the piston means would tend to reverse and close the release valve and reopen the supply valve E3, due to which the piston means would tend to again move in the original direction, resulting in what is known as pumping. Such action might even occur on reducing the pressure of iluid in the pipe 1 as above described. It has, however, been found that the dash-pot structure using control pipe pressure in the dash-pot chamber l1 andgchoke 42, plus the restricting means for limitingfthe rates of supply and release of fluid under pressure to and from chamber I6 effectively prevents pumping and renders the power piston means Bil stable and accurate in adjustment. Moreover this structure permits the desired prompt change in position of lever 23 in response toa change in pressure in the control pipe l.

In thev above described operation ittvill be noted that pressure of fluid in the power `chamber i6 acting on the operating rod 3S isopposed and offset by the same pressure of 'fluid acting in chamber 54 on the ball-like structure 52, .so as to have no effect upon the controlling `pressure in chamber t acting on diaphragm Y5. l

ln case of failure of the supply of fluid pressure on an airplane, as to pipe '5, it is desirable that the different controlling devices on the engine automatically operate to insure continued operation of the engine at an adeduaterspeed to maintain the airplane in the air. The motor above described and shown in Fig. l of the drawing may be employed for ycontrolling the richness or temperature of the fuel mixture to the engine, and in case of loss of the supply of controlling fluid pressure to pipe it is desirable that the controlling lever 23 be automatically moved back to its normal position, in which it is shown in the drawing, to provide a rich fuel mixture to the engine or a fuel at a temperature which will insure against freezing of moisture in the fuel supply line.

This automatic return of lever 23 to its normal position is obtained in case of loss of the supply of fluid pressure to the control pipe 'l and diafluid under pressure in phragm chambert by means of the regulating spring SS. It will be seen that if the pressure of fluid in chamber o is lost, the spring 36 acting through link i5 and rod 3o will rmove ange "t3 on the valve control membeiujol into engagement with surface 'la on member l5. This will open the release Vvalvel to` release any and -w-ill then pull the piston means @t to its normal position in which it is shown in the'drawing, at `which time the follower 33 secured to diaphragm 5 will substantially contact the stop shoulder 3l inthe cover. It will noted that "with the parts of the motor in their lnormal positions, as-shown in l, the. clearance space between the dia-v phragm follower 33 and shoulder '3l equals sub-- stantialzy the space betweenV the flange 'lffon valve control member 6l and surf-ace 'llt Ionfthe member 'l5 secured to the power pistonv means 3Q, whereby the above described positioning of the power piston means fs-twill be assured in case of loss of fluid pressure inthe control pipe 5l.

Description-Jig. vZ

The structure shown in Fig. 2 is ,particularly adapted for controlling the throttle or `rspeedof the engine above referred to and diiier's from the structure shown in Fig. 1 of the drawing, par-A ticularly, in embodying means for automatically moving the control lever 2&3 to a position Vinterfmediate its two extreme positions, .incase of loss of the supply of controlling fluid, .'so'as to thereby provide .s ufncient fuel to the engine, under such a condition, v.to ensure operationV of the engine at a speed above idling and sucient to maintain the Vairplanein flight.

.The motor Vshown in Fig. 2 comprises a cas-V ing made up of two casing sections 'llV andA 'i3 which are secured together by screw-threads in a manner shown in vthe drawing; .A t thejunction of the two sections, theV casing se'ctiohjlfhas a shoulder '9 overlying one `end of a :piston `bore provided in `the section'l'l between the section i6 and wall it. In this piston', bore is s lidably mounted a piston at. The adjacent lendof the regulating spring Sein this structure is jsupported by the piston Sil, in contrast to being supported by the wall :i in the structure shown in Fig. l of the drawing.

The casing section-ll .has secured to the outer end thereof the cover 3 and carries the differential'area .piston means 3%', 'the valve controlirneinberl 6l', the supply valve e3, release valve 6l',- etc. all o f'the detailsof'which are'identical to corresponding parts `vo'f'thenmotor. shown in Fig. An operating rod 8l, replacing the rod S9 in the structure lshownin `l, 'is mountedfto slide' in a bore through the wall 'ii and at :one end is secured to the valve control memberil within the power Vpiston chaniberfl Within lthe wall l is a ring S2 having sealing and sliding contact with the peripheral surface Y.of the operatingrod 8l ifo-r preventing leakage yof -uidfunder Apressure to the Apower piston chamber 'liifrom 1.a chamber 83 located between the wall fan'd the adjacent side of piston z8d. The opposite sideyof piston BB is subject to pressureof fluidgin chamber 8 which is open to the iiuid pressure release passage 9.

The piston Sii is provided Ywith an annular groove in which is disposed a ring 8d `having sealing and sliding contact with the wall of the piston borefor preventing lleakage of fluidfrom chamber 83 to chamber 3. The .operating rod f extends through a bore in pistonft'i intochamber 2,41's,3so

8, and within said bore said piston carries a seal-V operating rod 8| is provided with an annular collar 86 for contacting piston 80.

The operating rod 8| is provided, in chamber 8, with an enlargement 81 having a counterbore, the open end of which is closed by a cover 88, and slidably mounted in this counterbore is a piston 89. The piston 89 has oppositely extending stems 90 and 9|, the stem 90 extending through a bore in cover 88, while the stem 9| is mounted to slide in a bore in the operating rod 8|. The piston 89 is provided with a ring 92 having a sealing and sliding contact with the wall of the counterbore for preventing leakage of uid under pressure from a chamber 93 at one side of the piston to a chamber at the opposite side, which latter chamber is open to the fiuid pressure release passage 9 by way of a passage 94 and chamber 8. A sealing ring 95 is provided around the stem 9| to prevent leakage of fluid under pressure from an axial bore 96, extending through the piston 89 and stems 90 and 9|, to the side of said piston which is open to chamber 8 through passage 94, while a ring 91 is provided in cover 88 and has sealing and sliding contact with the piston stem 90 for preventing leakage of fluid pressure from chamber 93 to chamber 8.

'The diaphragm 5 is clamped between the two followers 98 and 99 and the piston stem 90 extends through the follower 98 and diaphragm and has screw threaded engagement with follower 99 for clamping the followers centrally to the diaphragm. The follower 98 is engaged by the adjacent end of the regulating spring 38. The axial passage 98 is open at one end to the control chamber 6, and is connected by a port |00 to chamber 93. The inner end of passage 98 registers with a passage `|0| Aextending through the operating rod 8| to the supply valve chamber 82. The rod 8| is provided with a port |02 connecting the axial passage IUI to chamber 83. Chamber 83 is connected by a passage |03 to the dash-pot chamber |1, and in this passage is the choke 42.

Operation-Fig. 2

When fluid at the normal minimum pressure of eighty pounds, above mentioned, is provided in pipe 1 and diaphragm chamber 6, this fluid pressure will equalize through passage 96 and port |00 into chamber 93, and, at the same'time, will also equalize through passage |0| and port |02 into chamber 83, and through passage |03 and choke 42 into the dash-pot chamber Fluid at this minimum pressure provided in chamber 83 will move the piston 80 into contact with shoulder 19 and thereby compress spring 36 to thefsame degree as provided bl'l wall 4 in the motor shown in Fig. l. The piston 80 will then remain in this condition during all normal operation of the motor, i. e., in response to variations in pressure in pipe 1.

. The normal or minimum pressure of fluid in chamber 6 will deflect diaphragm 5 against the opposing force of spring 36 to the normal position in which it is shown in the drawing, and this same pressure eiective in .chamber 93 on piston 89 will hold said piston against the inner end of its cylinder in contact withthe end of the operating rod 8| to provide, in effect, an unyield- Cil ing and rigid connection between the diaphragm 5 and the operating rod 8|. With the parts conditioned as just described, the supply valve 63 will be closed, Ythe release valve 6l will be closed, andthe power piston means 30 will be in'sub stantial contact with wall 4, for the same reasons as hereinbefore described in connection with the motor shown'in Fig. l.

With the parts of the motor shown in Fig. 2 of the drawing conditioned as just described, said motor will operate in the same manner as the motor shown in Fig.1 in response to variations in the pressure of fluid in the control pipe 1, above the normal minimum` pressure of eighty pounds. to selectively position the lever 23 in any desired position out of and including the normal position in which it is shown in the drawing. Y

The dot and dash line |05 indicates an intermediate position of lever 23 Vwhich, it will assume when the pressure of fluid in the control pipe 'l is at a certain degree such as 115 lbs. which is in excess of the normal minimum pressure. With this motor connected for controlling the speed of the engine, let it'be assumed that this position of lever 23 indicated bythe dot and dash line |05 `will provide for operation of the engine at the chosen speed required formaintaining the airplane in flight, as `for instance,`half speed, and to which position it is desired that the lever automatically be moved in case of loss of iluid under pressure from pipe 1, in contrast to being moved to the normal position, as occurs with the motor shown in Fig. 1. I

In case the pressure of fluid in the control pipe 5 and diaphragm' chamber 6 is lost, due to a ,broken pipe or the like the pressure of fluid in piston chamber 83 and in the dash-pot chamber I1 will at the same time be released. Upon this release of uid under pressure from diaphragm chamber 8, the spring 36-will deflect the diaphragm to a positionl inV which thefollower 99 substantially engages the stop shoulder 31. At the same time, the pressure of spring 36 will move piston into contact with the casing wall 4. If at the time of loss of fluid pressure from pipe 1, the engine is operating at a speed in excess of the chosen speed above mentioned thismove ment of the diaphragm' and thereby'of piston 89, will move said piston into contact with cover 88 and then act through rod 8| to pull the valve control member 6| into contact with member 15 and then through said member to operate the lpiston means 30 and'rod 20 to draw the lever 23 back to its intermediate position, indicated by the dot and dash line |05, in which position the vcollar 86 on the operating rod 8l will engage the piston 80 4which is in contact with the casing wall 4, whereby movement of the lever 23 past Vsaid intermediate position will be prevented. If at the time the pressure of fluid in the control pipe is lost, the engine is operating at a speed less than the chosen speed above mentioned, then movement of the pistonf80 into contact with wall 4 will act through the collar 86 and rod 8| to move the valve control member 6| into contact with surface 68a on the piston means 30 and then actuate said piston means and rod 20 to move lever 23 to its intermediate position for accelerating the engine, and at the same time the diaphragm 5 will deflect to the position determined by substantial contact between follower 99 and shoulder 31, and in which position the piston 89 will be in contact with the cover 88 to prevent movement of lever 23 past intermediate position.

It Will thus be apparent that regardless of the 2,4431, ssc;

position' of lever 23, or regardless of the'speed of the` engine at the time of lossof fluid under pressure from pipe 1, the motor shown in Fig. 21 will operate automatically tomove the lever 231 toits intermediate position and to then securely hold it against movement out ofsa-id position, to'thereby insure that the engine. will continue to-operate as intended.

Summary lrom.. the above description it will now be. ap.- parent. that we have provided an improvedfluid motor of. the type embodying; auidpressureao- Y siftion; andi being movable: relativeY to saidl power tuated power portion and a fluid pressure. controlled-pilot portion which may be. relatively small, compact, light in weight, sensitivetovariations in. control pressure, positive. andI accurate in adjustment according. tochanges in the control pressure, and which is automatically operative in case of failure of the supply of Controlling fluid pressure to move the device being controlled to a preselected. position.

HavingA now described ourinvention, whatwe claim as` new and desireto secure; by-Letters Paltent'isz.`

1.l A fluid motor comprising a` casing having a control chamber andV a power chamber, regu-lat'- ing spring means in said casing, pilot piston means in said. casing subject to opposing pressures of said regulating springA means and ofk uid in said control chamber, valve means in said casing for controlling pressure of fluid in said power chamber, said pilot piston-means being movable against said spring means upon an increase in pressure of fluid in said controll chamber to eiect operation of said valve means to supply fluid under pressure to said power chamber and' being movable by said spring means upon a reduction in pressure ofY fluid in said control chamber` to effect operation of said valveA means to release fluid under pressure from said power chamber, power piston means in said casing subject to pressureor uid'in said power chamber and adjustable to one position when pressure in said power chamber isfof one degree and adjustable to another position when the pressure i-n said power chamber is of greater degree, meansoperable by said spring means uponl loss of uid? under pressure in said control chamber to move said'l power piston means, and means operableV to limit movement of said power'piston means by said regulating spring means to a position intermediate said one-and another positions.`

2. A iiuid motor comprising a casing having a uid pressure control chamber and a fluid pressure power chamber, power-piston means in said casing subject to and adjustable by pressure of fluid in said'powerrcha'mber, valve means in said casing operable to supply uid under pressure to said power chamber, regulating spring means in said casing, pilot piston means in said casing subject to pressure of said regulating spring means and opposing pressure of fluid in said control chamber, other piston means in said casing operable by pressure of uid in said control chamber to condition said regulating spring means for controlling said pilot piston means, said pilot piston means being movable, with said regulating spring means conditioned to control said pilot piston means, relative to said power piston means upon an increase in pressure in said control chamber to effect operation of said valve means to supply uid under pressure to said power chamber to cause movement of said power piston means in a direction away from a normal popiston meansupon a-reduction in pressure in said control chamber toeffect operation of. said valve meansto release fluid under pressure from said power chambcrtocause movement'of said power piston meansv intheopposi-tedirection, andmeans associated with said: pllot piston` means and with the said other pistonmeans operable by said-reg ulating spring means'lupon loss of fluid under pressureA from said control chamber tol move-said power piston means to andtohold same in a position out oi'saidnormallposition.

3. A uid motor comprising a casing, a lever having a fulcrurn connection with-saidcasing-, and having a certa-in range of'movement, regulating spring means in said casing, piston means in said casing arranged to control said movement of said lever and controlled by said spring means and opposing pressureof fluid in a control chamber andfoperable upon an increase# in such pressure to effect movement of said lever in onedlrection and operable by said spring means upon a reduction in pressure"V of fluid' in said chameber to effect movement of' said lever in the' opposite direction, piston means in said casing sub-v ject to and operable by' pressure of fluid-in; said control chamber to render-said regulating spring meansY eiiectiveto control positioning of said lever by operation of the first' named piston means; said regulating spring means'being operable upon loss of fluidV under pressure Yon the second named piston means to eiect movement thereof to a certain position, and meansA operable by' said second' named pistonV means upon movement to said certain position to move saidA lever* to an intermediate position within its range;

e. .e fluid'K motor' comprising aA casing having a power chamber and a control chamber, powerpi'stonL means .in said casing subject 'to andadjustable in accordance with pressure of uid in said power chamber, pilot piston means in said casing arranged in coaxial relation with said power piston means and subject to and' adjustableinfaccordance with pressure of uid. in said. control chamber; valvemeans in said casing operable to supply fluid under pressure to saidpower chamber, a memberv arranged' in coaxial relation with said power piston means and' cooperable therewith upon axialV movement to ei'ect operationof saidlvalve means,.means separate from said pilot piston means carrying said member and valve means, and means connecting. said member to said pilot piston. means. and' 'operable upon, axial movement oi said pilot piston means to elect movementof said member, said means providing for movement. oifsaid'pil'ot.pistonmeans relative to said member ina. direction to rock the axis ofsaid pilot pistonmeans; Y

5. A Huid motor comprising a casing having a power chamber and a control chamber, power piston means in said casing subject to and adjustable in accordance with pressure of'fluid in said power chamber, said casing having a wall forming one end of said power chamber, pilot piston means in said casing arranged in coaxial relation to said power piston means and controlled by pressure of uid in said control chamber, regulating spring means arranged in coaxialV relation with said pilot piston means and acting thereon in opposition to pressure of fluid in said. control chamber, valve means for controlling supply and release of fluid under pressure to and from said power chamber, a member arranged in coaxial relation with said pilot piston means and cooperable with said power piston means I upon movement of said member in one direction to effect operation of said Valve means-to supply fluidV under pressure to said power chamber and upon movement of said member in the opposite direction to eiect operation of said valve means to effect a releaseof iiuid under pressure fromsaid power chamber, said wall wholly carrying said Valve `means and member, means connecting said pilot piston means to said member, said pilot piston means being operable upon an increase in pressure in said control chamber to `actuate said means to move said member in the said one direction, and said regulating spring means being operable upon release of fluid under pressure from said control chamber to effect movement of said member in the opposite direction. A

6. A fluid motor comprising a casing having a powervchamber and a control chamber, power piston means in Vsaid'casing subject to and ad- `instable in accordance with pressure of fluid in said power chamber, said casing having a wall forming one end of -said power chamber, pilot piston means in said casing arranged in coaxial relation to said power piston means and controlled by pressure of iiuid in said control chamber, regulating spring means arranged in co-A axial relation with said pilot piston means and acting thereon in opposition to pressure of fluid in said control chamber, valve means for controlling supply and release of uid under pressure to and from said power chamber, a member arranged in coaxial relation with said pilot piston means and cooperable with said power piston means upon movement of said member in one direction to effect operation of said valve means to supply fluid under pressure to said power chamber and upon movement of said member in the opposite direction to eiect operation of said valve means to effect a release of fluid under pressure from said power chamber, said wall carrying said valve means and member, means connecting said pilot piston means to said member, said pilot piston means being operable upon an increase in pressure in said control chamber to actuate said means to move said member in the said one direction, and said regulated spring means being operable upon release of fluid under pressure from said control chamber to effect movement of said member in the opposite direction, said means' being so constructed as to render said pilot piston means tiltable relative to said member in' directions to rock the axis of said pilot piston means., f '7. A fluid motor comprising a casing having a power chamber, a control chamber, a dash-pot chamber and a constantly open communication between said control and said dash-pot cham bers, choke means in said communication adapted to restrict flow of fluid under pressure into and out of said dash-pot chamber, a combined control and fluid pressure supply pipe connected to said control chamber and normally charged with fluid at a pressure in excess of atmospheric pressure, dilerential area piston means in said casing having at one side a relatively large area subject to pressure of fluid in said power chamber and having at the opposite side a smaller area subject to pressure of lluid in said dash-pot chamber, pilot piston means in said casing subject to pressure of fluid in said control chamber, regulating spring means in said casing opposing pressure of fluid on said pilot piston means, valve means in said casing for controlling pressure of fluid in said power chamber, said pilot piston means being movable against said spring means upon an increase in pressure of fluid in said control chamber to a position corresponding to the degree of such increase and being operable upon such movement to effect operation of said valve means to supply fluid under pressure from said pipe to said power chamber, said pilot piston means being movable by said spring means upon a reduction in pressure of uid in said control chamber to a position corresponding to the degree of such reduction and being operable upon such movement to effect operation of said valve means to release fluid under pressure from said power chamber, said power piston means being movable relative to said pilot piston means upon an increase in pressure in said power chamber and upon a reduction in pressure in said power chamber to effect operation of said valve means to bottle the fluid pressure in said power chamber in a position of said power piston means correspondingto the positionvof said pilot piston means, said power piston means having a normal position corresponding to the position cf said pilot piston means assumedv with said pipe charged with fluid at the normal pressure andv having another position corresponding to the position-of said pilot piston means when subject to a maximum pressure of fluid in said pipe, and spring control means operable by pressure of fluid in said pipe to condition said regulating spring means for controlling the operation-of said pilot piston means to effect corresponding positioning of the power piston means, said spring means being operable automatically upon loss of uid under pressure from said pipe to effect operation of said spring control means and of said pilot piston means. to effect movement of said power means to and then hold same in a position intermediate said normal and other position.

JOHN W. RUSH. ARTHUR J. BENT. 

